Development of a Monte Carlo collisions model for simulating laser-matter interaction, magnetically confined plasma, and inertially confined plasma*

The TriForce Institute for Multiphysics Modeling is developing a hybrid fluid-kinetic simulation framework for modeling fluids and plasmas in a wide range of environments, such as laser-matter interactions, inertial confinement fusion, and magnetic confinement fusion. The suite of numerical tools under development utilizes heterogeneous computer architecture and leverages the benefits of particle-based simulation techniques. In this study, we present the development and verification of a kinetic model for simulating collisional processes within the particle-in-cell framework. Advanced techniques are used such as energy-conserving second-order particle pushing and binary elastic and inelastic collisions between charged, neutral, and photon macroparticles. The model is verified through a series of tests with analytic solutions or previously published simulations. Then, we apply the model to study several different plasma physics problems: (1) hydrogen plasma and closed field line formation in a field-reversed configuration (FRC), (2) the propagation of fusion burn waves in compressed deuterium-tritium and proton-boron, (3) stimulated Raman backscattering to amplify a seed laser pulse in the presence of plasma and a pump field, and (4) power delivery in magnetically-insulated transmission lines. The FRC is found to have unusual stability, in agreement with experiments, and is a candidate for an innovative future fusion reactor. The model is then applied to proton-boron problems involving aneutronic fusion to identify a burning regime capable of achieving gain. Raman laser amplification in plasma is compared to experiments wherein high efficiencies and significant gain have been achieved. Lastly, we present improvements in high-voltage power flow modeling for pulsed-power science.